Quasi-liquids

Fig. 5. A growth model of a nanocapsule partially filled with a crystallite of rare-earth carbide (RCj for R = Y, La,. . . , Lu R,C4 for R = Sc) (a) R-C alloy particles, which may be in a liquid or quasi-liquid phase, are formed on the surface of a cathode (b) solidification (graphitizalion) begins from the surface of a particle, and R-enriched liquid is left inside (c) graphite cage outside equilibrates with RCj (or R3C4 for R = Sc) inside.

Several growth mechanisms of nanotubes have been proposed so far—e.g., open-end growth model (54), quasi-liquid tip model (29), and so forth. Here, we describe the quasi-liquid tip model for the growth of MWNTs. 

Figure 4.10. Kuroda s model explaining the repeated Habitus change of snow crystals [23]. Shaded areas are crystals dotted areas are QLLs (quasi-liquid layers).

Most metals always condense in crystalline form, but the grain size is extremely small at low temperatures (in the order of a few micrometers) and increases markedly with increasing substrate temperatures. Grain size decreases with increasing deposition rates, The condensation of amorphous or quasi-liquid phases at low temperatures has been observed for such metals as antimony and bismuth and a few dielectrics. Some of these materials, on annealing, pass through otherwise unobserved and probably metastable phases. 

A close connection exists between the presence of a flexible polymer skeleton and the flexibility of the bulk material. Macromolecular flexibility is often defined in terms of the glass-transition temperature, Tg. Below this temperature, the polymer is a glass, and the backbone bonds have insufficient thermal energy to undergo significant torsional motions. As the temperature is raised above the Y g, an onset of torsional motion occurs, such that individual molecules can now twist and yield to stress and strain. In this state the polymer is a quasi-liquid (an elastomer) unless the bulk material is stiffened by microcrystalfite formation. Thus, a polymer with a high Tt is believed to have a backbone that offers more resistance to bond torsion than a polymer with a low 7 g. 

The nanocrystals of such type form in various liquid media, such as organic solution [77, 81] or the softened quasi-liquid glass [82, 83], where there are no steric hindrances for the growth of equilibrium crystals without surface defects. At the same time, barriers for aggregation of clusters or atoms to metal nanocrystals in solid system that arises during the cryochemical solid-state synthesis favor the formation of crystals with structural defects,... 

Spiropyrans have been incorporated as photochromic moieties into many polymers [4,67]. Krongauz and his co-workers [68-72] have extended this work to include several types of SCLC polymers. Small molecule LC materials containing a spiropyran moiety have not yet been reported, presumably because typical spiropyrans are not sufficiently elongated. The covalent attachment of spiropyrans to rodlike mesogenic groups does afford quasi liquid crystals compounds with unusual metastable mesophases [4]. However, these compounds do not show LC... 

The problem in question is really very complicated. Here we have many potential possibilities formation of quasi-liquid hydrogen in cavities of nanomaterials, physical adsorption of hydrogen molecules, absorption of H-atoms, formation-rupture of covalent C-H bonds with possible eluation of carbon in the form of gaseous hydrocarbons. But the complicity of the problem cannot create obstacles to the true science. As every new field, chemistry of hydrogen in carbon nano-materials requires serious and all-round experimental investigations. Only such investigations can precede to theoretical treating of the phenomenon and be the criterion of the accuracy of different theoretical constructions. 

NitroBIPS having in the 5 -position (4 -X-benzoyloxy)-benzylidenamino substituents (128), where X is cyano, methoxy, and n-hexoxy, form amorphous films exhibiting birefringence when colored. The bulk materials exhibit quasi-liquid crystalline properties, intermediate between supercooled liquids and mesophases, which are attributed to the interactions between small ordered domains of the spiropyran molecules.149... 

F. P. Shvartsman and V. A. Krongauz, Quasi-liquid crystals of thermochromic spiropyrans. A material intermediate between supercooled liquids and mesophases, J. Phys. Chem., 88, 6448-6453 (1984). 

Concerning a possible role of ions in tropospheric trace gas processes little can be said at present. Besides ion-molecule reactions, ion-ion recombination and ion-catalyzed reactions may in this respect be important. The latter may also include quasi liquid phase reactions occurring in relatively large cluster ions or polyions. Maximum rates for trace gas destruction and formation are similar to those estimated for the stratosphere (see section on Potential Role of Ions in Stratospheric Trace Gas and Aerosol Processes). 

Thus far, four mechanisms for the formation of concentric shell carbon particles as zero-dimensional carbon allotropes have been proposed. The first mechanism is the formation of a corannulene carbon framework followed by a spiral-shell growth [48], The second mechanism is that the regular concentric arrangements of carbon layers in the onion-like caibon sphere occur tlirough the solidification process of a carbon droplet under ultrafast condensation (49J. The third mechanism is due to a solid—>quasi-liquid—>solid process tliat is, reorganization of soot-containing tubular and polyhedral graphitic particles by... 

The diagram in figure 2 contains at least one phase such that its existence has been noted only recently (Brostow, W. Dziemianowicz, T.S., Hess, M., Saboe, Jr., S.H. Liquid Crystals, submitted), namely the quasi-liquid (q-1). This is the material which was in the amorphous state below its glass transition Tg, but now is in the temperature range between Tg and the melting transition. Thus, q-1 can undergo crystallization - the so-called "cold crystallization" - in distinction to an ordinary liquid which cannot. 

---